1. Field of the Invention
This invention pertains to fuel delivery systems, and more particularly to systems for delivering gaseous fuel to internal combustion engines.
2. Description of the Prior Art
Various types of fuel delivery systems have been developed for internal combustion engines. For example, carburetors have been in use for many years and are now highly refined. Similarly, direct fuel injection systems are well known and in widespread use.
A common characteristic of prior fuel delivery systems is that the fuel is vaporized at locations either within or very close to the combustion cylinders. In carburetor systems, the carburetor is invariably located adjacent the engine intake manifold. In direct injection systems, the fuel is not vaporized until it is actually inside the combustion cylinder. In both types of systems, therefore, a pump is required to deliver liquid fuel from a storage tank to the engine.
Despite their general suitability for automotive applications, both carburetor and direct injection systems have certain disadvantages. Both types of systems require high accuracy, and therefore expensive, components for proper operation. Especially with direct injection systems, those components include costly high pressure injector pumps. Both carburetor and direct injection systems are highly susceptible to failure from dirt, moisture, and other contaminants, and servicing a failed system requires skill and unproductive down time. In addition, the prior systems are not able to readily change the air/fuel ratio of the vaporized fuel.
Thus, notwithstanding past technological developments in automotive fuel systems, further refinements to fuel delivery is highly desirable.